Basics of ignition and diagnostics of no spark. FS80AV

Hello,

I hope somebody can help. I'm learning so please excuse any daft assumptions.

I have an old fs80av. I got it running beautifully until all of a sudden the recoil starter cracked and flew off. (screw holding it came loose) it carried on running for a short while then stalled.

I tried to get it started with a battery operated drill. Nothing.. I checked for a spark. Nothing. Changed the plug still nothing.

I then thought I would strip to see if all wires were intact. All appeared fine.

I tested voltage when turning her over and got readings although very low less than 1v and obviously fluctuating
I tested resistance between body and end of plug wire which returned 10ohms. and end of plug 16ohms

Firstly I presume that my cutoff switch seems as though it has had it. as if I test between between crank case and wire I get continuity no matter if my switch is on or off.

however on that point .. excuse really daft Question.. do i presume correctly by thinking Kill switch should complete circuit with ground/ earth to kill or break circuit and stop ignition?

Also how can i make sure my spacing is correct on this? I cant align stator and position as there is no shaft on which to centre the flywheel.

I hope somebody can assist.

I know that you have a stihl engine, but this old Kohler manual, section 8 does an excellent job explaining how the ignition system works. If you do a search you can get a service manual for your unit. Hope this helps.

http://www.mymowerparts.com/pdf/Koh...al-K91-K141-K161-K181-K241-K301-K321-K341.pdf

Thanks for the Kohler pdf. I see ref to 11.5k ohms. but this is a 4 stroke.. 11ohms is close to what i have. However the only ref to stihl i found was 5-7kohms.
What do you think of this and the other results obtained?

Regards

As per the Kohler manual, I have taken reading from switch wire to .. well it says mounting bracket which there is none. So i presumed the "forks".
HERE is a link to a photo of module.. red line represents from where to where I have taken reading.
It does show continuity so i presume it is dead?
Can somebody please confirm I have taken the correct reading and my conclusion is correct?

Regards

I suspect you may have a bad coil, but before replacing set the gap between the coil legs and the magnets at .010 inches. Sorry I don't know the metric conversion. Testing resistance on magneto systems is not an exact science, but that being said, I feel that 11 ohms between spark plug lead and ground would indicate a shorted secondary lead or coil. Normally should be between 10K-17.5K depending on the size of the coil.

It was my mistake.. 10 000 Ohms. not 10 ohms. However 0 resistance between switch wire and the prongs.. as red in pic.

Would you still assume a short?

Lining up the coil is tricky bacuase of access to screws and no way to centre flywheel correctly. That also poses a problem.